Post navigation

Post hoc ergo propter hoc

One of my favorite shows is The West Wing and there is an episode of the same name as this post. Unfortunately for you, Aaron Sorkin is a better writer than I.

That said, this concept, “After it, therefore because of it” is a common mistake many of us make when forming theories. It’s related to the concept that correlation is not causation.

I was reminded of this the other night when another phrase entered my mind: “Rain Follows The Plow”. This was a hopeful theory in the 19th century that as settlers settled past the 100th Meridian, the rain would follow where they plowed. Simply put, by farming the land, rainfall would increase.

The theory sounds a bit perverse until one considers that for awhile, increased rainfall did seem to increase as the more land came under the plow. So, there was some basis for the idea at first. The correlation seemed to match. However, this just ended up being a short-term climate change.

Unfortunately the theory was also a product of the idea that humans were the center of creation. As the subsequent Dust Bowl and other issues showed however, this theory was, (excuse the bad pun) all wet.

Sometimes correlation is not causation and we should not let our all too human biases influence our theories.

Fortunately, properly done, science is eventually self-correcting. Scientists make mistakes, but over time, the winnowing process eliminates them. The idea of scientific racism was once extremely popular, but over time has clearly been shown to be false. The idea of an ether was shown to be false.

Meanwhile, other theories have continued to hold up to intense scrutiny. As weird as quantum mechanics appears to be, evidence continues to mount that much of the current theory is in fact correct. When scientists discover particles that travel faster than light the default assumption continues to be (and so far correctly) that there is an error in the experiment.

Not much of a moral here other than just because the rooster crows when the sun rises, don’t mistake the crowing for the cause of the sunrise.